Editing Picea engelmannii (section)

==Ecology==
[[File:Picea engelmannii Sierra Blanca NM.jpg|thumb|left|upright .6|Young Englemann Spruce seedling]]
Because transpiration is greatly reduced in small saplings while engulfed in snowpack, increased rates of [[transpiration]] in response to loss of snowpack, coupled with low sapwood water reserves and an extended period of soil frost in windswept areas, may prevent Engelmann spruce from regenerating in open areas both above and below the tree line. Both water uptake and water stored in [[root]]s appear to be critical for the survival of subalpine Engelmann spruce saplings that are exposed above the snowpack in later winter to early spring.<ref name="boyce">Boyce, R.L. and Lucero, S.A. 1999. Role of roots in winter water relations of Engelmann spruce saplings. Tree Physiol. 19:893–898.</ref> 

For exposed trees, the availability of soil water may be critical in late winter, when transpirational demands increase. Cuticular damage by windblown ice is probably more important at the tree line,<ref name="hadley1">Hadley, J.L.; Smith, W.K. 1983. Influence of wind exposure on needle desiccation and mortality for timberline conifers in Wyoming, USA. Arctic Alpine Res. 15:127–135. (Cited in Coates et al. 1994).</ref><ref name="hadley2">Hadley, J.L.; Smith, W.K. 1986. Wind effects on needles of timberline conifers seasonal influence on mortality. Ecology 67:12–19. Cited in Coates et al. (1994).</ref> but damage caused by desiccation is likely to be more important at lower elevations.<ref name="boyce" />

Despite wind damage, the species tends to grow taller than others at the tree line.<ref name=":02" /> It is [[shade tolerant]], but not so much as [[subalpine fir]], rendering it somewhat [[Fire ecology|dependent on fires]] to outgrow competitors, although its thin bark and shallow roots make it vulnerable to fire.<ref name=":02" /> [[Dendroctonus rufipennis|Spruce bark beetles]] attack the tree, being particularly deadly to groups which have stood for centuries.<ref name=":02" /> It is also susceptible to avalanches.<ref name=":02" />

Although older spruce forests are not very useful to animals for forage, they can become so after fires, as they often burn completely, allowing many other plants, especially deciduous, to rise.<ref name=":02" /> Engelmann spruce-shaded streams are exploited by [[trout]], <ref name=":02" /> and [[aphid]]s produce [[gall]]s which hang from the tree and look similar to cones when they dry out.<ref name=":02" />